Various types of escalators capable of carrying a large-sized object such as a wheelchair have already been developed and put to practical use. All of these types of escalators look like an ordinary escalator in appearance but are provided with mechanisms for transforming a special group of steps into a level surface when it is necessary to transport the large sized object and an attendant's help is necessary for operating the mechanism and placing the object. Accordingly, ordinary users are excluded and it is necessary that the traveling operation be suspended for a considerably long time, giving rise to a problem that ordinary users have to endure inconvenience. In addition, the escalators of the aforementioned types are generally complicated in structure and costly. Further, a rise of the wheelchair carrying step is twice or three times as large as that of an ordinary rise, thus impeding passengers' steps. There has also been proposed an escalator capable of carrying a large-sized object, in which separate tracks are provided individually for one or two additional steps added to an ordinary step so as to form a step for carrying a large-sized object and for an intermediate step intervening between an ordinary step and the additional step, thereby eliminating the need for the transformation mechanism. Because of an increased number of tracks, however, it is difficult to put this type of escalator into practical use. Meanwhile, a wheel stopper conventionally used is a retractable type.